The Development and Validation of the Impact of Multiple Sclerosis Scale and the Symptoms of Multiple Sclerosis Scale

McMillan L, Moore KA. The development and validation of the Impact of Multiple Sclerosis Scale and the Symptoms of Multiple Sclerosis Scale.ObjectiveTo develop and validate the Impact of Multiple Sclerosis Scale (IMSS) and the Symptoms of Multiple Sclerosis Scale (SMSS) using the Extended Disability Status Scale (EDSS) for construct validity.DesignPanel design involving test-retest over 4 months.SettingA mailed survey.ParticipantsVolunteers with a diagnosis of multiple sclerosis (MS) recruited from an MS support service in Australia: 193 people (mean age, 39y) and 150 people participated at time 1 and time 2, respectively.InterventionsNot applicable.Main Outcome MeasuresPrincipal components analyses, the Cronbach α, and descriptive statistics for the 2 scales; correlations for construct validity with the EDSS and retest; and confirmatory factor analysis to test the stability of IMSS and SMSS components over time.ResultsThe IMSS yielded 5 independent and reliable components; the SMSS yielded 3 components; both component structures were stable over time. These scales showed convergent validity with the EDSS.ConclusionsThe IMSS and SMSS are psychometrically sound scales suitable for clinical and research purposes to assess the symptoms and impact of MS.